It is known that microorganisms or microorganism-derived enzymes can be used as catalysts in hydrolysis of nitrile compounds to produce carboxylic acids such as optically active .alpha.-hydroxy acids (see Japanese Laid-Open Patent Publication Nos. 99495/92, 99496/92, 218385/92(=U.S. Pat. No. 5,223,416, =EP-A- 0449648), 84198/90(=U.S. Pat. No. 5,283,193, =EP-B- 0348901), 99497/92(=U.S. Pat. No. 5,234,826, =EP-A- 0473328), 192189/93(=U.S. Pat. No. 5,326,702, =EP-A- 0486289), and 237789/94(=EP-A- 0610048)) and amino acids (see Japanese Laid-Open Patent Publication Nos. 317394/89, 117493/91, and 79894/92).
As compared with such conventional processes, the hydrolysis of nitriles by a nitrilase gene cloned by genetic recombination is expected to drastically improve the catalytic ability of microorganisms because they can be engineered to contain multiple copies of the same gene.